Exit flow effects of the axial fan on the aerothermal performance of a two-fin model

The fan-sink assembly consisting of an axial fan and a fin array is widely used for cooling electronic devices. The axial fan provides nonuniform, unsteady, and turbulent flow. We performed computational-fluid dynamics (CFD) calculations and particle imaging velocimetry measurements to investigate how axial-fan-derived flow affects the flow and thermal fields of fins. The velocity profile obtained via CFD was used as the inlet boundary condition for the fin. In the fin part, a two-fin model was placed in three representative locations-hub, flow, and edge regions-based on the fan-exit flow features. The flow field and heat transfer were different at the three relative locations. In the hub region, owing to recirculation downstream of the hub, the velocity and heat transfer distribution were highly nonuniform. In the flow and edge regions, the velocity and thermal fields were asymmetric because of deviation caused by the tangential component of the swirl. In addition, the normal component of the swirl and expansion of the cooling flow led to secondary flow in the channel front, which affects the local heat transfer of the two fins.